Field of the Invention
The present invention relates to a cell balancing technology, and more particularly, to a cell balancing technology capable of reducing the number of components and reducing the area of a circuit.
Description of the Related Art
In general, a secondary battery refers to a battery that is capable to store energy and to discharge the stored energy for use. When a secondary battery includes one battery cell, a voltage may be restricted due to chemical or structural problems. Accordingly, in application fields in which a high voltage is necessary, a secondary battery may be configured with a battery pack in which a necessary number of battery cells is connected in series. Even when battery cells are manufactured under the same manufacturing conditions and the same environments, the battery cells differ in electrical characteristics. Therefore, when a plurality of battery cells are configured in one battery pack, an imbalance in a voltage or an imbalance in a remaining amount of charge between the battery cells connected to each other may occur under charger and discharge environments.
When a charge voltage of a battery cell is too high, there is a danger of a fire or an explosion. Conversely, when the charge voltage is too low, electrical characteristics may be lost. In order to prevent such problems, a secondary battery operates as follows when one of a plurality of battery cells is overcharged or under-discharged. That is, when some of the plurality of battery cells connected in series are overcharged more than the other battery cells, charging of the other battery cells is interrupted in an insufficient charge state. In contrast, when some of the battery cells are over-discharged, use of the charged energy is restricted in spite of the fact that the other battery cells yet have usable charged energy.
For this reason, the imbalance in a voltage or the imbalance in a remaining amount of charge between the plurality of battery cells connected in series may occur in the secondary battery. Further, a voltage range usable in each of the battery cells may decrease as charging and discharging are repeated or charging and discharging periods may be shortened, thereby shortening a lifecycle of each battery cell. In order to overcome such disadvantages, battery cell balancing methods have been suggested.
FIG. 1 is a diagram illustrating an energy consumption type cell balancing circuit according to the related art. The energy consumption type cell balancing circuit performs balancing of battery cells, consuming overcharged energy.
Referring to FIG. 1, an energy consumption type cell balancing circuit 100 according to the related art includes a voltage detection circuit 120 configured to detects an individual voltage of a plurality of battery cells B1, B2, . . . , and Bn connected in series and a processor 110 configured to control individual cell equalizers 131, 132, and 133 such that overcharged energy of a battery cell determined to be overcharged by the voltage detection circuit 120 is discharged using a resistor. The foregoing energy consumption type cell balancing circuit according to the related art has the disadvantage that energy wastes since the overcharged energy is emitted as heat via the resistor.
Accordingly, it is necessary to suggest an energy cell balancing method of reducing energy waste.